Then why do they do it? What is the supposed gain from producing your own parts, when mass produced parts like Shimano are available all over the world? Is it to increase sales of their repair services after the warranty ends?
They want to "re-invent the bike". They do (or did) produce some pretty new/innovative designs; I haven't really followed them since they went electric because I'm not that keen on electric bikes, but the original (non-electric) had the lock roll up inside the frame for example, which is pretty nifty. Lots of people also like the design from an aesthetic point of view.
"Use standard stuff" has a lot of value, obviously, but it also limits you. This is true for everything: from bike parts to the POSIX API or POSIX shell.
